Prognostic significance of metastatic lymph node ratio in node-positive colon carcinoma

Background: The aim of this study was to evaluate the prognostic significance of the lymph node ratio between metastatic and examined lymph nodes (LNR) in patients with stage III colon cancer. Methods: A review was made of 201 patients (106 men) with stage III colon cancer of R0 resection. Lymph node (LN) disease was stratified both by the American Joint Committee on Cancer and the International Union Against Cancer nodal staging system (pN) and by quartiles of the LNR. Survival curves were made by Kaplan-Meier analysis and assessed by the log rank test. Multivariate analysis was performed by the Cox proportional hazard model. Patients ranged in age from 22 to 82 (median, 59) years with median follow-up of 52 (range, 13-96) months. Results: The LNR increased as a function of the number metastatic LNs (P < .0001; 95% confidence interval [95% CI], .7155-.8265). Cutoff points of LNR quartiles to be the best separating patients with regard to 5-year disease-free survival (DFS) were between quartile 1 and 2, and between 3 and 4 (pNr1, 2, and 3); the 5-year DFS according to such stratification was 83.6%, 61.1%, and 20% in pNr1, pNr2, and pNr3, respectively (P < .0001). The Cox model identified the pNr as the most statistically significant covariate: pNr2 was three times (95% CI, 1.407-6.280) and pNr3 eight times more risky than pNr1 (95% CI, 3.739-18.704). Conclusions: Ratio-based LN staging, which reflects the number of LNs examined and the quality of LN dissection, is a potent modality for prognostic stratification in patients with LN-positive colon cancer.